It is important to emphasize, however, that occlusal adjustment should be performed in a given adult dentition only when there is absolute proof that the existing occlusal arrangement is in fact, harmful to some aspect of the masticatory system.
There are four fundamental mechanical objectives, which any occlusal adjustment must satisfy.
l. All-important overall emphasis in occlusal correction is the axial loading of the teeth during tooth contact in order to diminish destructive horizontal forces. It has long been observed clinically and proven mathematically that the attachment apparatus of the periodontium can tolerate vertical forces to a far greater degree than it cans horizontal forces.
2. A stale, adjusted intercuspal position must be established clinically coincident with the terminal hinge arc of closure. Although there is evidence that the reproducibility of this position may not be totally mathematically precise, it is the most reliable position that the clinician can use. In order to maintain a stable occlusion, the occlusion must be supported bilaterally upon the posterior teeth. In the intercuspal position coincident with the retruded contacting position, the opposing teeth must contact securely, bilaterally, and simultaneously.
3. There should be freedom of mandibular movement in all horizontals contacting positions and movements, that is, no cusp or tooth should impede or lock mandibular movement.
4. The occlusal vertical dimension must be created at a clinically acceptable level with an adequate amount of freeway space.
The posterior teeth support the occlusal vertical dimension. If the teeth have proper buccolingual landmark relations, the process of occlusal adjustment is most systematic.
Freedom of movement is accomplished by allowing the anterior teeth to separate the posterior teeth during horizontal contacting movements. In protrusive contacting movements the contact of the anterior teeth separate the posterior teeth. In lateral contacting movements the anterior teeth and the guiding cusps of the working side may help contribute to the working group function and thereby create the necessary interocclusal clearance on the nonworking side.
There are several reasons why the nonworking interference can pose problems during occusal adjustment.
1. There is a mechanical threat to the supporting cusp itself during grinding since nonworking interferences occur on the inner aspects of supportirig cusps. It is therefore possible that a supporting cusp will be disarticulated from the IC position by nowrorking correction.
2. The patient is confused about the source of the pain due to a nonworking interference. When pain results from excessive occlusal force it is difficult for the patient to avoid irritating the offending tooth if the interference occurs on the nonworking side. When the patient chews on the opposite side to avoid tooth contact, the nonworking interference will continue to cause problems.
3. Although occlusal wear may tend to diminish working contacting interferences, it can accentuate nonworking interferences. When there is a cuspal interference on the workiing side, the nature of occlusal contact is such that the FOA of the lower arch contacts the guiding incline of the upper arch. over time, the attritional facet on the FOA can decrease the severty of the interference. On the other hand, the nonworki，英语毕业论文，英语论文 |
